What study features make the evidence base for topical estrogen on skin credible?

When you look at the research on topical estrogen for skin, there are a few features that really help make the evidence feel solid. Here at Alloy, we lean on these same features when we review studies for our own products, including M4.

A big one is that many of the studies on topical estrogen, including estriol, were designed in ways that help reduce bias. Dr. Ellen Gendler talks about this in her conversation with Dr. Corinne Menn. Some trials were randomized, some were double blinded, and some even included skin biopsies to measure structural changes in the dermis rather than relying only on what people saw in the mirror. You can hear her explain this in more detail in the research section of their webinar here.

Another helpful feature is that this research has been around for quite a long time. Topical estrogen wasn’t invented recently. Studies go back to the 1990s and early 2000s, and they consistently show improvements in elasticity, firmness, hydration, and collagen. A classic example is the study referenced on our science page, where six months of topical estriol led to large reductions in wrinkle depth and pore size.

It also helps that the safety side is rooted in decades of data from vaginal estrogen. Those products are FDA approved, they have extremely minimal systemic absorption, and their long safety history gives researchers a reliable reference point when studying estrogen used on the face. That context supports what we see in estriol face cream studies, including findings that serum estrogen levels don’t rise with use.

If you want to dig deeper, our science page collects several of these studies in one place, including links to PubMed:https://www.myalloy.com/science/skin

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